public class Example4_13 {
    public static void main(String args[]) {
        Circle1 circle = new Circle1();
        circle.setRadius(196.87);
        Tixing lader = new Tixing(3,21,9);
        Student zhang = new Student();
        System.out.println("zhang计算圆的面积：");
        double result=zhang.computerArea(circle);
        System.out.println(result);
        System.out.println("zhang计算梯形的面积：");
        result=zhang.computerArea(lader);
        System.out.println(result);
    }
}


